Process for the production of hard polyurethane foams

Abstract

PCT No. PCT/EP93/01959 Sec. 371 Date Jan. 27, 1995 Sec. 102(e) Date Jan. 27, 1995 PCT Filed Jul. 22, 1993 PCT Pub. No. WO94/03515 PCT Pub. Date Feb. 17, 1994Rigid polyurethane foams are prepared by the reaction of 1) polyisocyanates with 2) compounds of a molecular weight of from 150 to 1500, having at least two hydrogen atoms active towards isocyanates and which one tertiary nitrogen atom in the molecule, in the presence of 3) hydrofluoroalkanes as foaming agents as well as optionally in the presence of 4) other auxiliary substances and additives known per se.

We claim: 
     
       1. A process for the production of hard polyurethane foams by reacting 1) compounds having molecular weights of from 150 to 1500, having at least two hydrogen atoms that are reactive with isocyanate groups, and having one tertiary nitrogen atom in the molecule, with   2) polyisocyanates in the presence of     3) foaming agents consisting essentially of one or more pure hydrocarbons, and, optionally,     4) other auxiliary substances and additives.   
     
     
       2. The process of claim 1, wherein component 1) comprises a polyether having a molecular weight of from 250 to 500. 
     
     
       3. The process of claim 1, wherein component 1) is a polyether which has been obtained by reacting triethanolamine with propylene oxide and/or ethylene oxide. 
     
     
       4. The process of claim 1, wherein component 1) is a polyether which has been obtained by reacting ethylenediamine with propylene oxide and/or ethylene oxide. 
     
     
       5. The process of claim 1, wherein said foaming agent comprises cyclopentane. 
     
     
       6. The process of claim 1, wherein said foaming agent is selected from the group consisting of n-pentane, isopentane, and mixtures thereof. 
     
     
       7. The process of claim 1, wherein said foaming agent comprises 2,2-dimethylbutane. 
     
     
       8. The process of claim 1, wherein said foaming agent comprises a mixture of n-pentane, isopentane, and/or cyclopentane.